MOTOBRICK.COM
TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Motorhobo on September 15, 2016, 07:43:58 AM
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The Maryland inspector says the rear rotor needs to have the thickness stamped on the rotor itself -- .18", which is supposed to be the service limit stated in the BMW service manual. But on P. 484 the Clymer says:
Thickness
Standard: 4.0 - 4.04mm (0.157-0.173 in)
Minimum: 3.55mm (.14 in)
0.18 in sounds like a new disk. I have two spares, each with ~.165 in. There is conflicting info on the other forums, like this one from Inge saying the K100 minimum front and rear limits are 3.55mm or .14 in.
http://www.k100-forum.com/t3602-minimum-and-maximum-thickness-of-brake-discs-for1984-non-abs-k100rt (http://www.k100-forum.com/t3602-minimum-and-maximum-thickness-of-brake-discs-for1984-non-abs-k100rt)
So the only way to get this through inspection is with a goddam new disk? That's absurd -- I ran a rear rotor down to, well I'm not going to tell you how thin because I'd be embarrassed to admit it, but definitely a hell of a lot thinner than 0.157.
Can anybody point to any official BMW info that says this .18 value is bogus? I'll go with the Clymer for myself but I'm not sure the inspector is going to be onboard with that.
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Can anybody point to any official BMW info that says this .18 value is bogus?
From the factory manual:
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From the factory manual:
Inge you are my f**king hero yet again -- glad I speak German.
So what's up with this .018 thing? Just a convenient number for selling overpriced brake disks?
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Inge you are my f**king hero yet again -- glad I speak German.
So what's up with this .018 thing? Just a convenient number for selling overpriced brake disks?
You'll probably need to supply DOT a notarized or letterhead verification from an authorized BMW dealer.
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So what's up with this .018 thing? Just a convenient number for selling overpriced brake disks?
From what I'm reading, the front and rear rotors had the same minimum specs until '94 when the rear was changed to the .18" spec using a different style rotor. The manual in Inge's post looks like its from '87. Maybe this was a US-only change. Clymer's should reflect that change but doesn't so the best recourse is—sadly—verification from a BMW service center, unless you're able to baffle and charm the mechano-bureauocrat.
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There doesn't seem to be a Service Bulletin concerning this change in MOTOBRICK.COM's K75/S/RT bulletin archives, either.
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So where are you reading that, Laitch? I just talked to a service guy at Hermy's in PA, one of the only old-school dealers left on the planet, and he found it very odd that any US Standard measurement would be stamped on any OEM BMW disk. He also found it odd that the 0.018 would be a minimum, since it's so close to new.
I personally am totally comfortable riding with a rear disk between .173 and .157 as stated in the manual, so I'm going to go try to convince the inspector that this is the correct value and that what's on the disk is the manufacturer's tolerance for a new disk, not the service range of a used one. We'll see how that goes :dunno2:
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Further to this, the early K100 rotor had some cracking issues and there was a recall -- I read something about the disk being made thicker, probably the thickness it is now. So maybe that's the root of the issue. It would be nice to know exactly what's up with this -- I daresay this won't be the last time it comes up, since the Maryland inspection sheet looks really detailed now. Up until 2013 it was basically "starts stops signals horn works = pass" but now there's all these measurements and specs on the sheet and the inspector kept the bike for 45 minutes using his caliper.
Anyway -- off to the inspector -- will report back on whether he wants to bust my nuts or not.
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Anyway -- off to the inspector -- will report back on whether he wants to bust my nuts or not.
Good luck. Pass around the doughnuts.
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There's a rear brake on a K75? i never knew what that thang was...
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Further to this, the early K100 rotor had some cracking issues and there was a recall -- I read something about the disk being made thicker, probably the thickness it is now.
The very early rear disc was slotted and the problem was that they did crack between the slots and
the outer circumference...........same thickness.
From what I'm reading, the front and rear rotors had the same minimum specs until '94 when the rear was changed to the .18" spec using a different style rotor.
This is affecting K1100LT's only.
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There's a rear brake on a K75? i never knew what that thang was...
Yes there is and I used the ch1t out of it trying to coerce the sidecar with the dog to stop when the rest of the bike and me stopped -- the disk was down to .103 -- minimum .140 -- thus proving that there's lots of meat left after even after your teeth hit the bone.
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Yes there is . . .
Many riders in the South have converted the brake pedal into part of a delivery system for Mountain Dew dispensed from a hose attached to the handlebar. kennybobby's bike probably has one of those.
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The very early rear disc was slotted and the problem was that they did crack between the slots and
the outer circumference...........same thickness.
This is affecting K1100LT's only.
I still don't understand what this stamp is doing on this disk. In inches, not the actual minimum rating, and on a part with the OEM BMW logo...so not aftermarket and not produced in USA, and definitely original off a K75. I just don't get it -- and sure would like to have some kind of explanation to give to the inspector :musicboohoo:
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I just don't get it -- and sure would like to have some kind of explanation to give to the inspector :musicboohoo:
Stand by. I've got a query in at MAX BMW, received an acknowledgement and am waiting for a second response. This lack of clarity is unfair to owners getting inspections and to the people administering them.
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Yaahoo--mountain dew! And we have the Moon Pie festival over here in Bell Buckle, TN
@hobo
remove that ABS tooth ring and get yer dremel tool after that stamped ring--soon that incorrect .18 will be gone...
The stamped ring is just riveted on to the brake disc and may refer to itself, not the brake.
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@hobo
remove that ABS tooth ring and get yer dremel tool after that stamped ring--soon that incorrect .18 will be gone...
Great idea, kennybobby! It'll only take a couple of deft flicks with a Dremel to change that 8 to a 3.
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+1 to Dremel time...
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Yaahoo--mountain dew! And we have the Moon Pie festival over here in Bell Buckle, TN
Sun Drop Golden Girl Cola was my drink of choice in Soddy Daisy back in the '70s. Carbonated raisin juice.
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0,18" is the min. thickness for the K11's........could the disc have been changed for a used one earlier?
Another strange thing BMW ETK doesn't recognize the part#, I have to look through some older discs.
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0,18" is the min. thickness for the K11's........could the disc have been changed for a used one earlier?.Another strange thing BMW ETK doesn't recognize the part#,
Yet another strange—my bike has the same .18" minimum casting—maybe there was an orgy of part swapping at the factory one day, just to relieve the constraint and boredom of orderliness and precision.
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I have to look through some older ETK discs.
Sorry, didn't find any info on that part#.
Maybe it was a change on the 75's around the same time as the 11LT's..........but it looks like a dark
secret, buried deep in the archives.
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0,18" is the min. thickness for the K11's........could the disc have been changed for a used one earlier?
Another strange thing BMW ETK doesn't recognize the part#, I have to look through some older discs.
No -- I have 4 of these disks, they all have the .18 stamp and three of them are guaranteed to have shipped with 94/95 K75s here in the US.
I'm going to the inspector now and will tell him there is a worldwide effort underway to figure this freaking thing out but in the meantime please refer to the German service manual and the Clymer.
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I guess the inspector was impressed by the page from the German service manual and the matching Clymer spec -- he accepted the lower, reasonable specs of .157 - .173 and minimum .140.
So the puzzle remains unanswered but that's no longer my problem -- hope the next guy also gets a reasonable inspector with no interest in senseless ball-busting.
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Very glad your inspector was a mensch...
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. . . inspector with no interest in senseless ball-busting.
That's not always the case. Vehicle inspectors take on considerable liability if they're working in the private sector like those in Vermont. Without clear evidence to the contrary—which you wisely provided—they must adhere to the standards they're given.
One inspector here was prosecuted for performing a substandard inspection that passed defective brakes (http://www.burlingtonfreepress.com/story/news/local/vermont/2015/08/11/mechanic-charged-manslaughter/31466163/)later found to contribute to a fatal accident. His negligence was gross but any negligence—no matter how benign it may seem—can bring similar consequences. That's why some inspectors are strict about the process.
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By senseless ball-busting I mean if I had provided solid information and documentation from two sources, i.e. direct from the OEM Service Manual and the Clymer, but the inspector had still persisted in requiring .18 thickness because that value appeared stamped in the metal, despite the fact that he had no proof that the value stamped into that metal actually did refer to the minimum thickness of the brake disk and not the actual thickness of the inspector's own tiny wee-wee.
Noone begrudges people doing their job -- people just generally don't like senseless ball-busters, and God knows there is no lack of those running around in positions of 'authority'. I consider myself lucky to have gotten a reasonable guy.
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He was probably influenced by your sensitive and pleasant personality, Motorhobo.
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:hehehe
Or my shameless pandering.
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Stand by. I've got a query in at MAX BMW, received an acknowledgement and am waiting for a second response. This lack of clarity is unfair to owners getting inspections and to the people administering them.
I just received a response from Jeremy at MAX BMW. His response just repeats what we already understand—that inspections vary from state to state and that inspectors can chose to impose the minimum clearance stamped on the carrier rather than published specs.
I asked him to explain why some carriers have this stamp but specs printed at seemingly every source for K75 bikes are at variance with what is stamped on the carrier, and I asked for documentation that can be presented at an inspection declaring the .18" spec an invalid one in these cases.
I believe he'll respond.
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Just wondering -- did you ask him what Max BMW would do if a customer came in with a rear disk under .18? Would they recommend that the disk be replaced? In other words, what specification does Max BMW observe? I mean, when customers come in, the dealer can't hem and haw -- they have to fill out a service order. Seems no one wants to say any words that reflect an actual position on it.
Except Inge who did one better than words by showing me the manual.
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Just wondering -- did you ask him what Max BMW would do if a customer came in with a rear disk under .18?
Jeremy tried to send me a BMW spec sheet but attached only a tag not the document in his email to me. I asked him to resend. I'll post the response with the document as a pdf that can be downloaded and presented to inspectors. This would be as an aid to members who aren't as charming as you, Motorhobo.
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Except Inge who did one better than words by showing me the manual.
I would say that what's stamped on the disc hub overrules the spec in the manual, as this change have
happened many years after the manual have been printed.
But it strange that it is so difficult to find any info about this.
Have searching a bit about this, and see that the question also have been raised in European forums....
but no one have an answer to this secret.
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But it strange that it is so difficult to find any info about this.
Have searching a bit about this, and see that the question also have been raised in European forums....
but no one have an answer to this secret.
I wonder how many people have paid unnecessarily for a new rotor if there is no published documentation to require it. It's possible it could be a production/assembly error for which nobody in the corporation has taken responsibility.
Jeremy's response should be incoming today.
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Searching a bit around it seems like the thicker brake (min. 0.18") discs is used on all ABS models.
Non ABS did follow later......could be that this was around the same time that the OEM brake pads
was changed from organic to sintered.
Only a dive into the deepest and darkest archive will reveale the secret.
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Only a dive into the deepest and darkest archive will reveale the secret.
This is what I received from MAX BMW. It probably looks familiar to you and Motorhobo, Inge. :giggles It can be inferred then that this is the specification they are following for all K75 models regardless. MAX hasn't explained anything about the .18"Minimum stamp so, like Motorhobo the trailblazer, this is probably what others should present at inspection if there's an issue.
I'm attracted to the idea of changing the .18 to .13 then dabbing on a matching metallic color to finish the project. cool shades
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Looks like the manual is just as old as that one I did copy from.....and before the ABS was introduced.
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Looks like the manual is just as old as that one I did copy from.....and before the ABS was introduced.
Looks like the spec hasn't quite made it across the ocean yet—to that dealer, anyway— and that's OK. :2thumbup:
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Using the Clymer and the OEM manual, my disk passed inspection at about .157. Again, my last disk was at .103 without failure, having been used heavily to help stop a sidecar with a 75 lb. dog. So AFIAC, the .14 minimum spec can be adhered to and the .18 value ignored without repercussions of a technical nature. It isn't an ABS related stamp because that same stamp is on the disk that shipped with my 94 non-ABS K75.
As to the riddle of the.18 stamp, since it's in American standard units I think it's reasonable to say that it was introduced early on in the production process to address some US-specific concerns, and then nobody bothered to remove it and in the meantime it's actual purpose has been forgotten. Maybe it's not a minimum use spec at all, maybe it's a spec for the minimum out-of-the-box thickness to distinguish it from an earlier version that was NOT .18 out of the box, like maybe perhaps the one that had the cracking problem or maybe even a short-term interim solution that was used here in the US before the Vaterland got its shit together enough to design and produce the next generation.
Anyone having to have their bike inspected should take these docs to the inspector before paying for the inspection to avoid unpleasant surprises. Inquire specifically which value the inspector considers applicable. Even if your disk is below .157, the inspector might say the .14 minimum throw-away value applies. That's what my inspector said -- as long as it's .14, it's a pass. But YMMV depending on your inspector -- I guess one could just as easily argue that the service range of .157-.173 applies and below .157 isn't acceptable for inspection purposes.
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It isn't an ABS related stamp because that same stamp is on the disk that shipped with my 94 non-ABS K75.
Non ABS did follow later......could be that this was around the same time that the OEM brake pads
was changed from organic to sintered.
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I get that, Inge, but it since only the US value is stamped, it seems more likely that the folks in Munich decided a good way to make money would be to put a bogus US value on the disk so that Americans could be compelled to replace more $400 disks. Kind of like how the folks in Wolfsburg decided they could sell more cars to Americans by by installing software that would output bogus emissons data.
Just sayin'.
Anyway, here's the Maryland inspection report with all the detail. I sure don't remember seeing anything like this last time I had a bike inspected here. Looks like the same form used for a cage. This might be the shape of things to come nationally.
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Hi, I have a 1988 K75S. I will attach pics of the disc.
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The minimum gets thinner...the plot thickens...and all of a sudden the decimal delimiter is a comma (the Euro way) instead of a period (the US way) like it is on my disks.
Lends credence to Inge's theory about the later K75s...but I'm still riding it down to .14 regardless of what the disk says.
Thanks for posting the pics...though I'm confusder now than before...
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The minimum gets thinner...the plot thickens...and all of a sudden the decimal delimiter is a comma (the Euro way) instead of a period (the US
Why are Europeans using commas and inches? I think the Tri-Lateral Commission is somehow involved in this.
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Why are Europeans using commas and inches? I think the Tri-Lateral Commission is somehow involved in this.
To make money and confuse Yanks, just like VW...except there was no such thing as software way back then so they had to do with hardware.
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To make money and confuse Yanks,
VW wasn't confusing Yanks. It was completely deceiving Yanks. It was also deceiving Europeans and South Koreans who also were enforcing emissions standards, and is the target of lawsuits in Germany and SK. Over here, we were last in line. Let's give credit were credit is due. :clap:
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You're right -- credit where due. VW got caught while BWM Motorrad USA is still selling disks with .18 cast in the metal and no one knows for sure why and they'll never get caught. It's the perfect scam -- everyone knows affluent white males can't be victims.
Problem is -- affluent white males aren't riding these bikes anymore, only us poor folk who do their own work. I say -- class action! Sue the bastards! Justice must prevail! Long live the Proletariat!
On the other hand, I passed inspection so f**k it.
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On the other hand, I passed inspection so f**k it.
An adept imitation of a populist firebrand, Motorhobo. It might be time to quit profiling and take your act on the road—now that you can ride on it legally.